In fairness, Mark, the cost to transition from a well-established version to another well-established version is not that bad. For instance from PHP 5.2 to PHP 5.5 or 5.6. By now, almost all of the dependencies and packages and plugins will have updated versions. You can still get into trouble and huge expense though with custom code. A lot of people who built WordPress sites early had to build a lot of custom code. Forcing them to spend thousands to rebuild is not exactly fair. I've noticed more and more people in our community like to tell others how to spend their money and how to run their website. That's why we wrote [BusinessPress](https://wordpress.org/plugins/businesspress/): to let a publisher easily update his/her site at his/her own speed.

Anyway if WordPress as a community are going to force people to update, forcing them to update to PHP 5.6 would be eminently more reasonable than PHP 7. It's a far easier upgrade and security upgrades are planned [until at least 1 Januar 2019](http://php.net/supported-versions.php).